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Finding the Fourth Proportional to 1,128.98, 1,691.07 and 641.78

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Solution

The fourth proportional to 1,128.98, 1,691.07 and 641.78 is: 961.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,128.98 : 1,691.07 = 641.78 : x
  2. Step 2: Convert to fraction form
    1,128.98/1,691.07 = 641.78/x
  3. Step 3: Cross multiply
    1,128.98x = 1,691.07 × 641.78
  4. Step 4: Simplify right side
    1,128.98x = 1,085,294.90
  5. Step 5: Solve for x
    x = 1,085,294.90/1,128.98
  6. Step 6: Final answer
    x = 961.31

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.